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PostPosted: Wed May 23, 2012 9:32 pm 
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Bottle Rocket

Joined: Tue Mar 27, 2012 9:38 pm
Posts: 7
Green Manalishi wrote:
I did the FX Loop Mod to 47pf, and the mud mod, and it just woke the amp up, sounds much better.

Very easy to do with good results.

Last mod forme is swapping out the black shadow and putting in a vintage 30.

This amp sounds killer thru my 4x12 with vintage 30s.
Could you please post your thoughts on how it sounds with the vintage 30. I'm planning on doing speaker swap on my 2x12 100. Was thinking of trying one 30 and one black shadow.


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PostPosted: Mon Jun 04, 2012 11:27 pm 
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Bottle Rocket

Joined: Sun Jun 03, 2012 11:08 pm
Posts: 11
Hello I am new to the forum and just completed all the mods but the Parallel to Series effects loop mod. All that I can say is my nomad 55 sounds incredible! Thanks to all for these mods!
And now for my question about the parallel to series mod:
I want to install a push pull pot, I can see from the schematic that it needs to be a 25k audio taper. My question is how should it be wired to go from series to parallel? Also I'm hoping that I don't need to run a patch cable from the send and return jacks after the mod to get signal.
Thanks!


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PostPosted: Tue Jun 05, 2012 12:44 pm 
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Mark II
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Joined: Thu Jun 09, 2011 1:05 pm
Posts: 57
The push/pull pot eliminates the need for a patch cable. If you are not running any effects through the loop put the loop in parallel mode with the mix control all the way up.

You may have trouble finding a 25K push pull pot (I did). You can use a 50K pot and shunt a resistor of roughly 50K (a 47K or 51K should be fine) across terminals 1 and 3 of the pot.

The wiring for the push/pull is to leave the pot as is in one position, and in the other position directly connect leads 1 and 2.

You would leave lead three attached to the terminal of the pot. Disconnect leads 1 and 2 from the pot and attach each one to a separate common pole of a DPDT switch. In one position of the switch, run leads from the pot to one side of the DPDT switch so that in that position the pot is engaged. In the other position of the switch, run a jumper across the poles so that 1 and 2 are connected in that position and 3 is not in the circuit.

I hope that makes sense.


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PostPosted: Tue Jun 05, 2012 8:51 pm 
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Bottle Rocket

Joined: Sun Jun 03, 2012 11:08 pm
Posts: 11
Thanks Recluse for the info. As soon as I get the parts I will replace the stock part with the push pull potentiometer. Looking forward to hearing this mod too!


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PostPosted: Tue Jun 05, 2012 11:10 pm 
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Mark II

Joined: Fri Dec 02, 2011 10:19 pm
Posts: 124
Updated the NFB mod with a parallel resistor/pot variation and added the FX loop patch cable tip.

Thank you for the continued learnings.


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PostPosted: Wed Jun 06, 2012 9:58 am 
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Bottle Rocket

Joined: Sun Jun 03, 2012 11:08 pm
Posts: 11
What would be the best tubes for the nomad 55 post mods?
I currently have jj audio el34s for the power amp section and electro harmonics 12ax7's in the pre-amp section, with a Phillips 12at7 in the last slot.


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PostPosted: Thu Jun 07, 2012 1:13 am 
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Bottle Rocket

Joined: Sun Jun 03, 2012 11:08 pm
Posts: 11
Hey Nomad express,
Your mod looks great, Love the pics! I already did the 1mega ohm push pull pot variation or else I would give it a whirl...


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PostPosted: Tue Jun 12, 2012 12:10 am 
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Bottle Rocket

Joined: Sun Jun 03, 2012 11:08 pm
Posts: 11
Just installed the push pull 25k pot and wired it up for the series or parallel effects loop mod. Took out the old pot and replaced it with this mod and it sounds much better in series. I love the option of being able to still use the pot for mixing the dry signal with a wet one and I hooked up a multi effects processor to make sure everything was in working order. But the amp sounds so good now with all the mods that I think I won't even bother to use outboard effects! Thanks again to Recluse for the help in wiring up the pot! All of these mods I highly recommend to all Nomad users.


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PostPosted: Tue Jun 12, 2012 8:30 pm 
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Mark II
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Joined: Thu Jun 09, 2011 1:05 pm
Posts: 57
Glad it worked out. I wasn't sure my description of the Push/Pull Mod was clear enough.


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PostPosted: Wed Jun 13, 2012 1:19 am 
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Bottle Rocket

Joined: Sun Jun 03, 2012 11:08 pm
Posts: 11
Oh yeah dead on. Thanks again!


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PostPosted: Tue Jun 18, 2013 1:52 pm 
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Mark I

Joined: Tue Jun 18, 2013 1:47 pm
Posts: 31
want to do the parralell/series mod with the dbdt switch just want to verify that wire #3 stays connected to pot even when 1 and 2 are in jumped position. the original non switched version of this mod has #3 detatched and insulated

_________________
Ibanez s2 cu24, Ibanez Prestige S 1520FB, ernie ball volume, bad horsie 2 or crybaby,keely modded ts9, ocd, mesa Mark V combo, G-system (fx loop),, rjm mini amp gizmo, avatar 412 cab.


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PostPosted: Wed Oct 29, 2014 5:30 pm 
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Bottle Rocket

Joined: Sun Jun 03, 2012 11:08 pm
Posts: 11
I posted this in modern amps but didnt get a reply, so I am posting it here, too.
My Nomad 55 combo has developed a hum. Anyone know what could be causing a hum in the red channel? The other two channels are fine. Changed all my tubes thinking that would solve it.
Still there. Idea's anyone? Someone told me could be the power transformer going bad, but if it was that wouldn't the hum be present across all three channels?

Thanks in advance...


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PostPosted: Sat Nov 08, 2014 10:39 am 
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Mark II

Joined: Tue Jan 07, 2014 10:54 pm
Posts: 70
boogieman2012 wrote:
I'm new to the forum and want to say thanks for the info. Gonna try these mods but I have one question. I bought the 47pf cap and its a 1kv. Is this cap ok to use or should I go back and order the 50v? 1kv is all they had in stock at the moment. Sorry to bring up an old thread but I dont want to mess up here. Thanks again for any response.


A lot of these mods do not address the real problem...
the power supply is not stiff enough to start with.

If you would just double the value of the capacitors in the B+ supplies,
then most of the problems would be solved.

For example, the preamp uses 22uF caps in the high voltage supply...
you should replace all those with 47 uF instead.
Go down the line, all the way thru to the power amp, and double all those HV capacitor values.

Above all, you should do this first, and decide if "any" of these other mods are actually necessary.
The information I just gave you eliminates the need for most or "all" of these mods! The Nomad will sound like a whole new amp, just by swapping out the HV capacitors with doubled uF values...

AND while you are at it...
As long as the board is out, to change the capacitors, install sockets for all the ICs and Relays.
This will save an enormous amount of time, in servicing the amp.
When a relay fails, you can swap it in 10 minutes...instead of removing the entire circuit board to change 1 relay.

Importantly, inexperienced people should not work on this amplifier.
The circuit board is very easily damaged by improper soldering. This is NOT the amp to "learn" on.
If you do not have professional tools and equipment, hire a technician instead to do the updates.

Nomad 45:
The caps that are changed are in the power supply, not the FX loop.

Specifically, The cap at point "C" in the power supply should be changed from 10uF to 47uF
The cap at point "D" in the power supply should be changed from 10 uF to 47 uF
The caps at point "B" in the power supply should be changed from 2X 10uF in parallel, TO 2X 22 uF in parallel.

At point A in the power supply, following the standby switch, you have 6 resistors in series.
220 ohm,365 ohm, 365 ohm, 365, 365, 365...
then you come to a 10uF filter cap. Change that cap to 22uF.
That's a wrap for stiffening the power supply.
Then at V1 input, pin 7, you should install a 68K resistor in series with the ferrite bead.

That cleans up the performance quite a lot. It's just about perfect now.
Sounds like a whole new amp. The sag and mud are gone, the highs are way clearer.
You can crank the gain much higher, without any oscillations (motor boating) occurring.

However, you should have a professional do it for you.
I do not recommend that inexperienced person attempt this update.
The circuit board must be removed to do this update. And, it must be done very carefully.

Then, there are issues:
as long as you have pulled the circuit board, carefully test ALL the mechanical 6 volt relays.
A worn out relay will cause problems. Make sure your relays are all good, before you put it back together.


Last edited by soundguruman on Sat Nov 08, 2014 12:15 pm, edited 2 times in total.

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PostPosted: Sat Nov 08, 2014 11:35 am 
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Mark II

Joined: Tue Jan 07, 2014 10:54 pm
Posts: 70
Jonom wrote:
I posted this in modern amps but didnt get a reply, so I am posting it here, too.
My Nomad 55 combo has developed a hum. Anyone know what could be causing a hum in the red channel? The other two channels are fine. Changed all my tubes thinking that would solve it.
Still there. Idea's anyone? Someone told me could be the power transformer going bad, but if it was that wouldn't the hum be present across all three channels?

Thanks in advance...


Change the 22 uF capacitors in the preamp high voltage supply to 47 uF, change them all.
This will eliminate the hum, buzzing noise, and will get rid of the muddy sound.

Importantly, inexperienced people should not work on this amplifier.
The circuit board is very easily damaged by improper soldering. This is NOT the amp to "learn" on.
If you do not have professional tools and equipment, hire a technician instead -- to do the updates.


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PostPosted: Sun Nov 09, 2014 1:31 am 
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Bottle Rocket

Joined: Sun Jun 03, 2012 11:08 pm
Posts: 11
soundguruman wrote:
Jonom wrote:
I posted this in modern amps but didnt get a reply, so I am posting it here, too.
My Nomad 55 combo has developed a hum. Anyone know what could be causing a hum in the red channel? The other two channels are fine. Changed all my tubes thinking that would solve it.
Still there. Idea's anyone? Someone told me could be the power transformer going bad, but if it was that wouldn't the hum be present across all three channels?

Thanks in advance...


Change the 22 uF capacitors in the preamp high voltage supply to 47 uF, change them all.
This will eliminate the hum, buzzing noise, and will get rid of the muddy sound.

Hey thanks for the reply Soundguruman!
I will get to swapping out the caps soon and see how she sounds.


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